The grouping of individual fiber-optical connections within a single pair of connectors has not been accomplished until now without severe shortcomings, such as poor transmission of light and excessive fragility. These shortcomings are particularly compounded when the hybrid connectors are used underwater or any other kind of severe environment.
To form a reliable optical signal connection, photons must travel in the same axial direction as the waveguide through lenses or fluids having the same index of refraction as the waveguide material. These requirements demand an exact control of the distance between the ends of the fiber's waveguides being connected and/or their associated lenses.
Connectors designed for use underwater are often installed on the interfaces of structures which are subject to tremendous pressure differentials between the inside of the structure and the outside which is exposed to the water pressure. If the pressure difference between the back of the connector and the mating interface exceeds the friction exerted by the body of the connector over the part of the conductor that passes through that body, the optical terminal might be dislodged and fly out of the connector. This is not an uncommon occurrence when connectors are mounted on a bulkhead separating the inside of a deep sea probe from the surrounding waters and in other submarine structures. This requires that underwater connectors exhibit great mechanical simplicity and sturdiness. Furthermore, they should be extremely easy to use due to the fact that underwater manipulation is often impaired by the use of diving suits and that connections and disconnections are sometimes achieved by means of remote devices and robots. There is therefore an acute need for a type of underwater connector that could group fiber-optical connections in a sturdy and easy-to-operate configuration.